Processing of centrifuged solids from liquefied coal

The centrifuged residues from coal liquefaction processes present two problems which the Pittsburgh ETC has found to be controllable by thermal processing of the material: the residues contain significant amounts of carbon and oil that should be recovered, and their sticky, malodorous, dough-like nature makes them difficult to handle. This paper reports the results of heat treatments using several types of processing equipment and two different temperature ranges. Pyrolysis in the range of 1,100/sup 0/ to 1,400/sup 0/F yielded 20 to 30 wt % of oil product, depending on the source of the residue and its initial oil content. Lower temperature heating (e.g., 600/sup 0/F) yielded less oil, but did produce a non-sticky friable solid. The percent oil yield was a function of temperature, residence time, and thickness of the layer exposed. A one-eighth inch thick sample became friable in 15 to 30 minutes exposure to 600/sup 0/F, during which time it lost about 13 percent of its weight. The tests included measurements on a steel conveyor belt, which could become the commercial embodiment of this treatment.